7.3 with 3:55
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Cross-Country
Joined: Jul 2024
Posts: 83
Likes: 33
From: Elgin/Rockport TX
7.3 with 3:55
Guys I’m looking for those who have experience towing a travel trailer with a 7.3 gas with 3:55.
I am looking at buying a new to me F250 7.3 but where I’m at it’s rare to find one with anything other than 3:55. I prefer to have 3:73 like the 2023’s and newer have but the 2023’s are more than I want to spend.
I have a 38’ travel trailer that weighs around 10,500 on travel day. I don’t typically travel where there’s a lot of hills but I do come across a few steep ones here and there. My biggest issue I come across is wind. Heading into a 20-25 mph wind is tough and my Ram 6.4 gasser isn’t working for me.
I appreciate real world info!
Thanks.
I am looking at buying a new to me F250 7.3 but where I’m at it’s rare to find one with anything other than 3:55. I prefer to have 3:73 like the 2023’s and newer have but the 2023’s are more than I want to spend.
I have a 38’ travel trailer that weighs around 10,500 on travel day. I don’t typically travel where there’s a lot of hills but I do come across a few steep ones here and there. My biggest issue I come across is wind. Heading into a 20-25 mph wind is tough and my Ram 6.4 gasser isn’t working for me.
I appreciate real world info!
Thanks.
Fleet Mechanic
Joined: Jul 2019
Posts: 1,316
Likes: 312
A 5% difference in RPMs is no problem that the transmission won’t overcome, like noted.
I suppose, according to the towing guide, what really matters is 1100# towing capacity and E-locker. If so, order what you want.
I suppose, according to the towing guide, what really matters is 1100# towing capacity and E-locker. If so, order what you want.
Logistics Pro
Joined: May 2021
Posts: 4,005
Likes: 2,330
The gear range select button is a very useful feature. If you find the truck needs some more RPMs, you can always lock out 10th, then 9th will be equivalent to 3.85 running 10th gear. If you lock out 9th and 10th, you get the equivalent of 4.78 8 speed gearbox.
I some times lock out 9th and 10th in hilly terrain to keep my speed in check on downhill sections without using the brake. But the transmission learns from your driving style so it largely depends on the driver.
I some times lock out 9th and 10th in hilly terrain to keep my speed in check on downhill sections without using the brake. But the transmission learns from your driving style so it largely depends on the driver.
Thread Starter
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Cross-Country
Joined: Jul 2024
Posts: 83
Likes: 33
From: Elgin/Rockport TX
Thanks for the replies! I manually change gears on my truck now as needed when pulling my camper. Mainly looking for those who have pulled with the 7.3 with 3:55. I know there’s a difference between 3:55 and 3:73 especially when pulling 10.5k lbs I just don’t know how big that difference is.
Mountain Pass
Joined: Jun 2024
Posts: 122
Likes: 80
The difference is 5% less RPM at a given speed and gear compared to 3.73, that's it. HP is pretty linear so you get 5% less HP at that gear and speed for climbing hills and pushing air. If that 5% is too much then you just drop a gear. With 10 gears there is plenty of granularity to find the optimum speed and gear for whatever you're towing. The difference mattered a lot more more 6 speed and lesser transmissions, not so anymore.
The folks who get 4.30 get the advantage of 9th and 10th overdrive gears still being relevant while towing, where 3.55 and 3.73 owners realistically can only tow camper trailers in 8th gear or less. So the 4.30 folks do get the advantage of some more RPM granularity when towing because they have more gear choice. The disadvantage is when they're not towing and 10th and 9th gear are complete power overkill for unladen highway driving reducing mpg and increasing noise.
The folks who get 4.30 get the advantage of 9th and 10th overdrive gears still being relevant while towing, where 3.55 and 3.73 owners realistically can only tow camper trailers in 8th gear or less. So the 4.30 folks do get the advantage of some more RPM granularity when towing because they have more gear choice. The disadvantage is when they're not towing and 10th and 9th gear are complete power overkill for unladen highway driving reducing mpg and increasing noise.
Trailering
Joined: Feb 2024
Posts: 21
Likes: 11
Thanks for the replies! I manually change gears on my truck now as needed when pulling my camper. Mainly looking for those who have pulled with the 7.3 with 3:55. I know there’s a difference between 3:55 and 3:73 especially when pulling 10.5k lbs I just don’t know how big that difference is.
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Cross-Country
Joined: Jul 2024
Posts: 83
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From: Elgin/Rockport TX
I have a 22 with the 7.3 and 3.55 gears. My bumper pull TT is 10k fully loaded. I usually lock out 10th gear and my truck has no problems holding 65 mph. I am in the midwest but do encounter some hills. The truck just motors right up, I will not use cruise when we get into some hilly locations FYI.
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4wd High
Joined: Oct 2016
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I have a 2021 with 7.3 gas and 3.55 gears. I tow a 26 foot travel trailer and have never had any problems handling hills. I travel to Arizona at least once a year and no issues. The trailer is not as heavy, it is around six thousand pounds.
Fleet Mechanic
Joined: Jan 2022
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I have 7.3 with 4.30 gears and it's probably overkill for our 38 ft 8k wet pull behind. It came in handy in the mountains or going up steep hills but I'd be just fine with 3.55. I'm generally not in a hurry when pulling my camper anyway, I upgraded to a SD truck for stability, not speed. All that being said if I went back I'd still order 4.30, but my truck sees 3-4k miles per year. So no experience with 3.55 but hopefully helpful in you making your decision.
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Cross-Country
Joined: Jul 2024
Posts: 83
Likes: 33
From: Elgin/Rockport TX
Thanks. I would consider 4:30 if they were available in a 250 in my area without having to get the Tremor package which comes with 35” tires that I’m not interested in.
What’s your fuel mileage like? Is that a 250 or 350?
What’s your fuel mileage like? Is that a 250 or 350?
Fleet Mechanic
Joined: Jan 2022
Posts: 1,410
Likes: 712
Mine is a 250 which was ordered with 4.30 by myself otherwise I doubt I would have found one as you've noticed. I looked at my overall lifetime fuel avg and it was 9.7 MPG the other day, that's probably 70% towing our camper then mainly the rest is city traffic, every once in a while it gets on the highway unloaded but pretty rare. 65 seems to be the sweet spot for best MPG towing, much more and it drinks quite a bit more. I would imagine I get high teens on the highway, but city traffic isn't much more than single digits I imagine. The MPG difference between 4.30, 3.73., and 3.55 is less than 1 MPG I would imagine, so don't factor MPG into your choice when looking at gearing in a truck IMO.
Thread Starter
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Cross-Country
Joined: Jul 2024
Posts: 83
Likes: 33
From: Elgin/Rockport TX
Mine is a 250 which was ordered with 4.30 by myself otherwise I doubt I would have found one as you've noticed. I looked at my overall lifetime fuel avg and it was 9.7 MPG the other day, that's probably 70% towing our camper then mainly the rest is city traffic, every once in a while it gets on the highway unloaded but pretty rare. 65 seems to be the sweet spot for best MPG towing, much more and it drinks quite a bit more. I would imagine I get high teens on the highway, but city traffic isn't much more than single digits I imagine. The MPG difference between 4.30, 3.73., and 3.55 is less than 1 MPG I would imagine, so don't factor MPG into your choice when looking at gearing in a truck IMO.
Fleet Mechanic
Joined: Jan 2022
Posts: 1,410
Likes: 712
Gotcha I appreciate the feedback. Like you 4:30 is probably overkill. I’m currently pulling my camper with a Ram 2500 6.4 gas 3:73 and it does fine unless there’s a strong headwind which does happen along the Texas coast. I have watched videos where many say about 1 mpg difference between 4:30 and 3:73 but that’s driving the 4:30 at 70 mph. At 75 it’s closer to 3 mpg difference from what I’ve seen. I drive 75% highway so sounds like for me 3:55 would probably be fine given I don’t pull that often (3 to 4 times a year on average).
FTE Community Team
Joined: Jan 2019
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Thinking back over the years of powertrain development, it's fun to watch this conversation. We're discussing locking out 10th and even 9th. Even then it is still in an overdrive ratio, towing lots of weight just fine, and happy about it.
10th = 0.6324:1
9th = 0.6871:1
8th = 0.8514:1 (~same as 6R140 5th gear)
7th = 1.0000:1 (same as 5R110 4th gear) (same as 4R100 3rd gear)
6th = 1.2773:1
5th = 1.5188:1 (~same as 6R140 3rd gear) (~~same as 5R110 3rd gear) (~~~near 4R100 2nd gear)
4th = 1.7733:1
3rd = 2.1319:1
2nd = 2.9186:1
1st = 4.6154:1
Rev = -4.6951:1
I agree with the others: the 10-speed takes a lot of the differential-ratio angst out of the picture.
10th = 0.6324:1
9th = 0.6871:1
8th = 0.8514:1 (~same as 6R140 5th gear)
7th = 1.0000:1 (same as 5R110 4th gear) (same as 4R100 3rd gear)
6th = 1.2773:1
5th = 1.5188:1 (~same as 6R140 3rd gear) (~~same as 5R110 3rd gear) (~~~near 4R100 2nd gear)
4th = 1.7733:1
3rd = 2.1319:1
2nd = 2.9186:1
1st = 4.6154:1
Rev = -4.6951:1
I agree with the others: the 10-speed takes a lot of the differential-ratio angst out of the picture.
Last edited by CathedralCub; Aug 2, 2024 at 01:32 PM. Reason: Decombined a long sentence for clarity